A control chart is a graphical tool to help determine if a process may be exhibiting non$-$random variation that needs to be investigated. If non$-$random variation is present, the process is said to be "out of control" otherwise it is said to be $"$in control." The following figure shows a control chart for a production line that fills boxes of cereal. Based on past data, we can calculate the mean weight of a box of cereal when the process is in control. The mean weight is $16\mathrm{.}05$ ounces. We can also calculate control limits$,$ an upper control limit $($UCL$)$ and a lower control limit $($LCL$).$ New samples are collected over time and the data indicates that the process is in control so long as the new sample weights are between UCL and LCL$.$ As shown in the chart, only sample $5$ is outside of the control limits$.$